In a portable Internet system, traffic for data transmission includes four QoS classes. The four QoS classes are respectively classified into an unsolicited grant service (UGS), a real-time polling service (rtPS), a non real-time polling service (nrtPS), and a best effort (BE) service. The UGS supports real-time transmission of fixed-size packets such as a voice over Internet Protocol (VoIP) on a periodic basis, and the rtPS supports real-time transmission of variable size packets such as an MPEG video.
In addition, the nrtPS supports transmission of variable size data bursts (e.g., a file transfer protocol, FTP), and the BE service supports transmission of traffic having lower priority such as e-mail and web-browsing. The above-noted QoS classes are combined with quality of service (QoS) parameters such as traffic rate, jitter, maximum latency, and error rate, and establish a specific connection. A plurality of connections may be established between a terminal and a base station depending on QoS, and each connection can be identified by a connection identifier (CID).
A transport connection between the terminal and the base station in the portable Internet system specifies connection-oriented access methods. Such a transport connection is identified by a CID and the CID is mapped to a service flow identifier (SFID) such that a QoS class for the corresponding connection can be identified. That is, all the CIDs contain at least one piece of QoS parameter information. In addition, mapping of an IP packet to a transport CID is designed to be performed through a packet classifier in the portable Internet system.
The packet classifier defines a plurality of classification rules for classifying an IP packet with a specific transport CID, and the rules are composed by a combination of IP header information, which includes a type of service (TOS), a destination address, a destination port number, a source address, a source port number, and a protocol type.
A packet classifier is connected with only one CID. Thus, in the portable Internet system, an IP packet is classified with a specific CID by the packet classifier and then transmitted. Therefore, an application having a real-time service characteristic must be mapped to a CID having the same QoS class (i.e., real-time service) and a packet classification rule of a packet classifier must be accurately established such that the application can be served with real-time services. A classification rule of a packet classifier that classifies downlink packets transmitted from a base station to a mobile station is applied by the base station, and a classification rule of a packet classifier that classifies uplink packets transmitted from the mobile station to the base station is also applied by the mobile station.
According to the portable Internet standard, a process for generating/changing/deleting a packet classification rule and a CID is the same as that of a service flow of a MAC layer. The service flow is generated, changed, and deleted through standardized processes such as a dynamic service add (DSA) process, a dynamic service change (DSC) process, and a dynamic service delete (DSD) process.
Through the DSA process, informative elements, such as QoS parameter for packet scheduling, a packet classification rule for classifying packets, and a CID allocated by the base station, are transmitted between the mobile station and the base station. The mobile station and the base station generate a packet classifier and a CID by exchanging the QoS parameter and the packet classification rule. In addition, a plurality of packet classifiers, each having the same QoS parameter, can be generated for one CID. For example, two packet classifiers for an e-mail or web-browsing packet can be mapped to one CID.
Herein, the e-mail packet and the web-browsing packet are classified in the same QoS class. In addition, a new packet classifier is added to a pre-established CID through the DSC process.
The DSC process transmits a pre-established CID and new packet classification rule information between the terminal and the base station. As a result, the base station and the terminal share the same packet classifier and CID information. A downlink packet classifier and a downlink transport CID are used for classifying and transmitting an IP packet from the base station to the terminal, and an uplink packet classifier and an uplink transport CID are used for classifying and transmitting an IP packet from the terminal to the base station.
However, it is difficult to identify a QoS class of the IP packet by using only the IP header information. Estimating QoS characteristics from the IP header information is related to how to define a packet classification rule of a packet classifier. The Internet Assigned Number Authority (LANA), an international Internet standardization organization, assigns a well-known port number for an application such that a client program accesses a server by using the well-known port number.
For example, a file transfer protocol (FTP) uses port 21, specifying transmission control protocol (TCP) or user control point (UCP) as a transport protocol, and a packet having the same protocol type and port number as above may have the same QoS as that of the FTP. However, it could be inaccurate to classify packets by using the protocol type and port number when substantial traffic data is transmitted/received because the protocol type and port number are used when the client initially accesses the server and they may be dynamically changed after the initial access.
On the other hand, forming an IP address of an Internet server as a classification rule can be a candidate solution. However, this method also has problems of difficulty and inefficiency of managing packet classification rules for all existing Internet servers. According to another method, an application program may insert QoS class information into a specific field of an IP header for classification of the IP packet. However, this method also has problems of developing an application dedicated to a portable Internet service and accordingly the application becomes incompatible with other typical applications.
To solve the above problems, Korean Patent Publication No. 2003-0043649 (entitled, “Method and apparatus for classifying service classes of packet data in two-way communication network”) provides a method for classifying a service class of packet data by measuring a total number of packet data for a predetermined time, determining a parameter based on whether the measured number of packet data is larger than a threshold value associated with a two-way communication characteristics of the packet data transmission, and calculating a value used to classified the service class of the packet data by using the parameter.
In addition, Korean Patent Publication No. 2003-0059075 (entitled “Frame classification for QoS-driven wireless LANs” filed in Jul. 7, 2003) provides a method for classifying a frame by using a frame classification entity (FCE) in a wireless local area network (WLAN). Further, U.S. Pat. No. 587,457 (entitled “Method for Connecting Data Flows” filed in Jan. 1, 2003) provides a method for supporting QoS between a terminal and a base station by mapping a QoS of an IP layer on a radio resource. However, the three prior arts cannot solve the above-state problems such as identifying a service class of a packet, identifying an exact point at which substantial data transmission starts, generation of a transport CID and activation time thereof, identifying QoS parameters of an IP packet, and comparability with a different application and cost reduction. Accordingly, a method for classifying an IP packet by using a transport CID is needed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.